This invention relates to the preparation of 4,4'-dipyridyls.
It is known that the electrolytic reduction of pyridine in aqueous dilute sulfuric acid yields piperidine, with a yield of over 90%. By-products of this process are 2,2'- and 4,4'-dipyridyl, both produced in minor amounts [F. Beck, "Elektro-organische Chemie" (Electroorganic Chemistry): 166, Chemie Publishers, 1974].
It is also known that 4,4'-dipyridyl can be produced by reacting pyridine with metallic sodium at about 100.degree. C. (e.g., U.S. Pat. Nos. 3,210,364; 3,210,367).
Furthermore, 4,4'-dipyridyl can be produced by the reaction of pyridine with metallic sodium in liquid ammonia in the presence of a large excess of dimethylformamide (Dutch Pat. No. 6,603,415).
However, the heretofore known processes for the production of 4,4'-dipyridyl are characterized by low yields and they can only be conducted with special safety precautions, because metallic sodium is used in most of the prior art processes.
Accordingly, it is a principal object of the present invention to provide a better process for the production of 4,4'-dipyridyls.
An additional object of this invention is to provide such a process which is relatively simple, safe, and economical.
A further object is to provide electrolytic bath compositions used in the process of the invention.
Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art.